1. Field of the invention
The present invention relates to insulating shaped articles based on inorganic fibers, especially plates, panels or molded articles, and to a process for the production of such shaped articles.
2. Description of the Prior Art
Shaped articles based on mineral or inorganic fibers are useful insulating materials which can withstand very high temperatures, for example as fireprotection panels, and as refractory insulating plates in thermal furnaces and combustion chambers.
The insulating shaped articles based on ceramic fibers or mineral wools are known products. In general, their preparation requires the use of an organic binder such as starch, polyvinyl alcohol or polyvinyl acetate. The binder content varies depending on the nature of the inorganic material, but generally ranges from 7% to 15% relative to the total amount of solids. Such amount of organic material presents several disadvantages, not only from an economic point of view but also from a technical standpoint. Indeed, when such insulating articles are subsequently subjected to high temperatures, they release large amounts of fumes resulting from the calcination of the organic materials. The destruction of the organic species during calcination causes a deterioration in the mechanical properties of the material. This is the more pronounced, the higher the content of the organic species.
Furthermore, such insulating shaped articles are generally prepared from an aqueous slurry from which the water is removed, for example by draining. With the organic binders heretofore employed in this art, the water removed still contains high concentrations of organic materials, thus reducing the content of the latter in the finished article. Furthermore, if this water is recycled, it is then necessary to readjust the binder content for subsequent manufacturing steps, while if the water is discharged into streams it creates pollution problems.